1. Field of the Invention
The present invention relates to a symbol information scanning apparatus for scanning symbol information such as a bar code.
2. Description of the Related Art
As a result of the growing use of POS (point of sales) systems, bar codes have become quite well-known to the general public. A bar code is a type of symbol including characters in the form of bars and spaces of different widths, which are arranged in parallel. When necessary, the symbol includes characters each having a check digit. The symbol also includes start and stop characters at the beginning and end, respectively, and margins next to the start and stop characters.
In Japan, the JAN (Japanese Article Number) code is a standard bar code and is widely used for consumer goods. The bar code is also used as a physical distribution symbol which is constituted by adding physical distribution identification codes of a single or double figure to the beginning of the JAN code.
The above types of bar code are so-called one-dimensional bar codes and are able to store information of at most several tens of bytes. However, as there is a growing demand for bar codes able to store larger amounts of information, various so-called two-dimensional bar code symbol systems have been developed. It is characteristic of the two-dimensional bar codes to encode considerably larger amounts of information than the one-dimensional bar code. One type of two-dimensional bar code is a stacked bar code which is formed by a plurality of one-dimensional bar codes to increase the amount of information. For example, a PDF-417 bar code is used as the type of stacked bar code.
A known conventional laser scan type apparatus is that disclosed in EP 0 384 955 A2 (Date of Publication of Application: 90.9.5), which is a symbol information scanning apparatus for scanning two-dimensional bar codes. In this apparatus, bar code symbol information is scanned by two-dimensional scanning of a laser beam and decoded. However, since this conventional scanning apparatus requires that users depress a scanning switch to issue a scanning start command, it cannot be operated automatically.